Question

Match the LIST-I with LIST-II 

Choose the correct answer from the options given below: 
 

• A. A-I, B-II, C-III, D-IV
• B. A-IV, B-I, C-II, D-III
• C. A-III, B-II, C-I, D-IV
• D. A-II, B-IV, C-I, D-III

Hint:

Associate keywords: Sickle cell $\leftrightarrow$ Malaria resistance (heterozygous advantage). Huntington's $\leftrightarrow$ Variable age of onset (penetrance/expressivity). PKU $\leftrightarrow$ Multiple symptoms from one gene (pleiotropy). Thalassemia Major $\leftrightarrow$ Severe/fatal homozygous state (lethal effect).

Answer 1

The Correct Option is D

Step 1: Concept Overview:
The task is to link specific genetic diseases to their corresponding genetic principles.
Step 2: Detailed Explanation:
- A. Sickle Cell Anemia: Heterozygotes (one normal, one sickle allele) exhibit malaria resistance, a prime example of heterozygous advantage. Thus, A corresponds to II.
- B. Beta Thalassemia (Major): The homozygous form of the beta thalassemia allele results in severe anemia, often fatal if untreated. This illustrates a recessive lethal allele, demonstrating a lethal gene effect. Hence, B corresponds to IV.
- C. Huntington's Chorea: An autosomal dominant disorder where the age of onset and symptom severity vary significantly, showcasing variable penetrance and expressivity. Therefore, C corresponds to I.
- D. Phenylketonuria (PKU): A single PAH gene mutation leads to diverse symptoms like intellectual disability and altered pigmentation, demonstrating a pleiotropic effect. Consequently, D corresponds to III.
Step 3: Solution:
The matching is: A $\rightarrow$ II, B $\rightarrow$ IV, C $\rightarrow$ I, D $\rightarrow$ III, which aligns with option (D).